The present invention relates to a burner for a furnace having at least one windbox that is supplied with air for combustion and has extending therethrough at least one such burner, which opens out toward a combustion chamber. At least one primary air channel is provided that is supplied from the outside with a coal dust/air mixture, and that is surrounded with at least one secondary air channel which in turn is surrounded by at least one tertiary air channel. Air can be supplied in a regulated manner from the windbox to the secondary and tertiary air channels.
A burner of this general type is known from EP 0 445 938 A1. With the known burner, a secondary resistor is associated with the input side of the secondary air channel. This secondary resistor comprises a side plate which is connected to the upstream end of the secondary air channel. Spaced at a distance from this plate is a further annular plate that surrounds the core air tube and is spaced from and disposed parallel to the plate that is connected to the free end of the secondary air channel. Rotatably mounted between the two plates are a plurality of flat individual vanes. The flat plates serve to establish the pressure loss by setting their angular position by means of a control unit and hence the establishment of a prescribed flow rate of secondary air into the secondary air channel. A corresponding arrangement is provided at the introduction end of the tertiary air channel.
This known arrangement requires a number of movable components, and does not permit a coupled adjustment of the air quantities being introduced from the windbox into the secondary and tertiary air channels.
It is therefore an object of the present invention to provide a burner of the aforementioned general type where it is easier to supply the secondary and tertiary air channels from the windbox.